352 W. G. Van Name — Bermuda Ascidians. 



Branchial aperture 6 or 8 lobecl, atrial aperture often with a 

 languet. 



Branchial sac generally long, with numerous rows of small round 

 or oval stigmata. It may be papillated, but no internal longitudinal 

 bars occur. 



Dorsal lamina with languets. 



Stomach-wall smooth or variously folded or pitted. Reproductive 

 organs and heart situated in the post-abdomen. Testis represented 

 by a number of small spermatic sacs. 



Gemmation by division of the post-abdomen. 



Geuiis Amarouciuin Milne- Edwards, 1841. 



Distinguished by forming massive, often pedunculated colonies, 

 with elongated zooids having long post-abdomens, usually six-lobed 

 branchial siphons, the atrial aperture placed well forward, and a large 

 atrial languet. The stomach-wall is, usually at least, longitudinally 

 folded, but in one of the Bermuda sj^ecies this appears to be a very 

 variable character. The post-abdomen is sessile. 



This genus, though almost universally accepted by writers on 

 Tunicata, is but poorly distinguished from Ajylidium Savigny, which 

 in its typical form has a sessile colony, shorter zooids, often lacks 

 the atrial languet, and has the post-abdomen separated from the 

 abdomen by a more conspicuous constriction or peduncle. The 

 atrial aperture is also said to be placed further back. Most of these 

 differences are very trifling, and many species could be placed in 

 either genus with equal propriety. 



Amaroucium bermudse, n. sp. 



Plate L. Figure 20. Plate LVIII. Figures 96 and 97. 



The colony is irregular in shape, seldom much over 30'°'" across, 

 generally less, with rather flat top and abrupt sides tapering into a 

 more or less distinct peduncle. The combined height of the colony 

 and peduncle often reaches 20'"'" or more. 



The test is firm, almost cartilaginous, but softer in the interior of 

 the colony. It is usually quite free from sand grains, grayish and 

 nearl}' opaque in life, sometimes with a distinct bluish or pinkish tint. 

 In formalin it becomes more transparent and of a yellowish or flesh- 

 color. There are no bladder-cells. The systems are irregular and 

 the number of zooids in different specimens of the same size is \Qvy 

 variable. 



